Sunday, Apr 08, 2012 at 13:10
@ Stan,
ok, it's a bit hard to understand for some:
you don't necessarily need a 'charger' to put the required amount of (over)charge into a battery.
If you had some faith in your battery seller, you would have approached them with the specific charging requirements of this type of batteries in cyclic apps.
And again, Battery Value comes to the rescue with some free advice:
Select a charger which offers a beefy current of at least one tenth of rated capacity, and which has a 14.7/14.8V setting.
If it's a multistage unit, it'll switch back to float at the end of the absorption stage.
At this point in time, disconnect your battery and hook it up to a 40~60W rated solar panel and put it in full sun for one hour.
This constant current charging treatment will make the battery lose some electrolyte which is the lesser evil.
Expect the charging voltage to rise beyond 16V during this.
This constant current treatment is essentially an equalisation charging stage which repairs spiral wound AGM batteries which were subject to PSOC operating conditions (at the cost of precious electrolyte).
@ Phil,
I'm confronted with similar questions on a daily basis (we're an AGM battery specialist retailer who actually communicate with clients AND battery manufacturers very closely).
Trust me, I understand full
well where Stan was coming from.
When someone says "I need to top up/restore", then this means nothing less than "repair" a battery which has suffered from the effects of operating in PSOC for some time.
Spiral wound AGM batteries are particularly vulnerable to these effects, thus they need an extra amount of overcharge to restore as much of the lost capacity as possible.
If that's not done, then it's all down
hill from here on.
On the other hand, applying a controlled overcharge according to the manufacturer's recommendations, makes the battery lose about 1~3 grams of electrolyte, so their cycle life is compromised.
And that's why spiral wound AGM batteries aren't really suitable for cyclic apps with lowish discharge currents down to below 30% of SOC.
Of course there are other applications where these shortcomings are being accepted for the battery's advantages like high current density, and mechanical ruggedness.
But flat plate AGM technology advances faster due to their lower cost of manufacturing.
You can now have equally high current density in flat plate AGMs at a fraction of the cost.
Look out for AGMs designed for start/stop systems.
cheers, Peter
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